Punch mechanisms

ABSTRACT

A punch mechanism for record members is disclosed which includes a die assembly consisting of a thin plate having a plurality of apertures therein for co-operating with a plurality of punches. The thin plate is bonded to a bolster which supports it over its unperforated area. The walls of the apertures in the thin plate are hardened and the remainder of the plate is relatively soft.

[ Dec. 18, 1973 United States Patent [191 Bailey PUNCH MECHANISMS Clevenger et a1.

Inventor:

Carlson...........

[73] Assignee:

Primary Examiner-Andrew R. Juhasz Assistant Examiner--W. D. Bray [22] Filed:

Att0rney-Keith Misegades et a1.

[30] Foreign Application Priority Data ABSTRACT May 26, 1971 Great Britain....... 17,227/71 U 8 Cl 83/23 76/107 C 83/637 A punch mechanism for record members is disclosed which includes a die assembly consisting of a thin rein for co- Cl plate having a plurality of apertures the 22 operating with a plurality of punches. The thin plate is bonded to a bolster which supports it over its unperfoes in the thin plate f the plate is rela- [51] [58] Field of Search...............

1 33; 76/1O7i156/293 299 rated area. The walls of the apertur are hardened and the remainder o tively soft.

[5 6] References Cited UNITED STATES PATENTS 2,553,615 5/1951 Wales 83/637 X 2 Claims, 1 Drawing Figure 1 PUNCH MECHANISMS BACKGROUND OF THE INVENTION The present invention relates to punch mechanisms for record members, such as punched record cards and paper tape, and in particular to the construction of dies for such punch mechanisms.

Punch and die assemblies for punching holes in record cards are known in which a plurality of punches co-operate with a plurality of apertures in a die. The die in such an assembly is generally formed from a single. block of metal. The life of such dies is not very long due SUMMARY OF THE INVENTION According to the present invention a punchmechanism for record members includes a die consisting of a thin plate having a plurality of apertures, the walls of the apertures being hardened and the remainder of the die plate being relatively soft; and a bolster supporting the die plate over substantially the whole of the unperforated area of the die plate.

Preferably the die plate is secured to the bolster by means of a layer of adhesive material.

BRIEF DESCRIPTION OF THE DRAWING I A punch and die assembly embodying the present invention will now be described, by way of example, with reference to the accompanying drawing which shows an'exploded perspective view of a punch and die assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing a die bolster 1 contains twelve round holes 2 positioned so as to correspond in pitch with twelve rectangular punches 3. The holes 2 are of a sufficiently large diameter that the punches 3 can pass therethrough'without contacting the walls of the holes. Raised projections 4 are formed on one surface of the die bolster l as shown together with raised pads 5. A preformed adhesive film 6 approximately 0.006 inch in thickness has cut out portions 7 and holes 8 formed therein. Die plate 9 is a thin plate containing 12 rectangular apertures 10, the apertures 10 being dimensioned and positioned so as to co-operate with the 12 punches 3. The die plate 9 is manufactured from a relatively soft steel but has the walls of each of the 12 apertures 10 hardened. A suitable material for the die plate is a steel of a type which can be surface hardened by a nitriding process, for example EN.4OB.

The manufacture of the die plate 9 is carried out in accordance with the following procedure. A steel plate of the required size is flattened and ground to a thickness of 0.055 inch. The steel plate is then copper plated to a minimum thickness of 0.001 inch and rectangular apertures are pierced and then shaved and broached to the required finished dimensions. After degreasing, the

plate is nitrided for 24 hours at a temperature of 500-5l0 C which hardens the walls of the holes to a depth of 0005-0007 inch the copper plating on the other surfaces of the die plate serving to protect these surfaces from the nitriding process. Finally the copper plating on the die plate is removed and the walls of the holes are blasted with small particles of glass having a grain size of 50 to 60 microns, this latter operation being effective to remove an oxide layer, having a thickness of 0.0003-0.0004 inch, which is formed on the walls of the holes during the nitriding process.

It has been found that by following the above procedure the walls of the holes are hardened to a value of 900-950 H.V. (Vickers Scale) which can be compared to a hardness value of 230-250 H.V. previously attained by manufacturing the die from a single block of metal and overall hardening.

The assembly of the die is carried out as follows. Three location mandrels 11, shown in broken lines, are positioned in three of the holes 2 in the die bolster 1. Each location mandrel 11 has a round portion at one end dimensioned so as to fit into one of the holes 2 and a rectangular portion at the other end which is dimen sioned so as to fit into one of the rectangular apertures 10 in the die plate 9. The adhesive film 6 is next placed on the die bolster 1, the cut out portions 7 and the holes 8 allowing the adhesive film to lie flat on the surface of the die bolster with the raised projections 4 projecting into the adhesive film and the location mandrels ll projecting through the-adhesive film. Finally, the die plate 9 is located on the location mandrels 11 and lowered until it rests on the raised projections 4. Cut out portions 7 in the adhesive film 6 ensure that the adhesive is kept clear of the rectangular apertures 10 in the die plate 9. The parts are clamped together by spring clamps in a fixture and the assembly is placed in an oven and heated to cause the adhesive to soften and fill the space between the die plate 9 and the die bolster 1 formed by the raised projections 4 which support the die plate 9 above the surface of the die bolster 1. Con tinued heating cures the adhesive which thereby bonds the die plate to the die bolster. It has been found in practice that with a projection height of approx. 0.003 inch and an adhesive layer having a thickness of 0.006 inch satisfactory results are obtained. After the bonding operation the upper surface of the die plate 9 and the raised pads 5 are ground to produce a flush surface, this operation reducing the thickness of the die plate'to 0.05] inch.

The remainder of the parts comprising the punch and die assembly will now be described. A stripper bolster 12 contains twelve round holes 13, positioned to correspond with the twelve holes 2 in the die bolster 1, and has a recess 14 positioned in its underside as shown. Prior to the operation of bonding the die plate 9 to the die bolster l the stripper bolster l2 and the die bolster l are correctly aligned with one another by two parallel tooling pins (not shown) which pass through holes 2 and 13 at either end of the assembly and whilst thus aligned the parts are drilled and clowelled. Dowels 15 allow the two parts to be separated and replaced in the same relative positions and screws 16 serve to retain the two parts in operating relationship. When the two parts are assembled together the recess 14 in the stripper bolster 12 ensures that a gap is provided, between the stripper bolster and the surface of the die assembly which is formed by the die plate 9 and raised pads 5,

through which a record card may be passed. The 12 holes 13 in the stripper bolster are counter-bored to a larger diameter from either end (shown in broken lines) to accommodate upper and lower bushes 17 and 18 respectively. The bushes 17 and 18 are a loose fit in the holes 13 and each bush has a rectangular aperture 19 passing co-axially through it. The rectangular apertures 19 are dimensional such that the punches 3 are a sliding fit therein.

The assembly of the die and stripper unit is carried out in the following manner. Twelve punch mandrels (not shown) which have cross-sectional dimensions identical to those of the punches 3 are inserted into the die assembly. A retaining plate 20, shown in broken lines, is placed over the punch mandrels, a protective layer of silicone paper (not shown) is placed on top of the plate 20 and the lower bushes 18 are slid on to the punch mandrels. The upper and lower counter-bored recesses of the holes 13 in the stripper bolster 12 are smeared with a cold setting adhesive and the stripper bolster is placed over the lower bushes l8 and located on the dowels 15. The upper bushes 17 are then placed on to the punch mandrels and lowered into the upper recesses of the stripper bolster. The top ends of the punch mandrels are lightly held in position with a tooling comb (not shown), the purpose of which is to support the mandrels without preventing the bushes from taking up their natural positions in the recesses. This method of assembling the die and stripper unit ensures correct alignment of the rectangular apertures in the two sets of bushes with the rectangular apertures in the die plate. When the cold setting adhesive has set the stripper bolster is separated from the die assembly and the punch mandrels are removed together with the retaining plate and silicone paper. Finally the stripper bolster is replaced on the die assembly and located by the dowels l5. Retaining screws 16 are fitted and the die and stripper assembly is now ready for insertion of the punches 3 and attachment to a punching machine.

The punches 3 are actuated by a mechanism (not shown). The actuating mechanism has not been described as'it forms no part of the present invention and furthermore suitable actuating mechanisms are well known. The punches are manufactured of tungsten carbide and when operating in cooperation with the hardened walls of the holes in the die plate provide a punch and die assembly having wear characteristics superior to the wear characteristics of previous devices.

Lubrication of the bearing surfaces between the punches and the bushes is provided for by a hole 21 which is drilled lengthwise through the stripper bolster. The hole 21 passes through each of the holes 13 between the upper and lower bushes. A greaser 22 enters intoone side of the hole 21 and a screwed plug 23 seals the open end of the hole.

Manufacturing the die plate in the manner described provides advantages in that the working areas of the die plate are hardened to a very high degree while the remainder of the plate remains softer and therefore more resilient and less likely to chipping or fracture than if the plate was hardened more extensively. Furthermore the use of a bolster in conjunction with the die plate enables the die plate to be of thin section thus simplifying the machining processes and reducing the stresses set up during the hardening process.

I claim:

1. Process comprising the steps of making a die plate containing a plurality of apertures corresponding one with each of a plurality of punches, a die support extending over an area substantially equal to that of the die plate, the die support also containing apertures corresponding one with each of said punches and having projections raised to a predetermined height on one face thereof, and a preformed adhesive film of a thickness greater than the height of the projections having cut-out portions the positions of which correspond to said apertures and said projections respectively;

positioning the die plate and the die support with their respective corresponding apertures in alignment, said one surface of the die support facing the die plates;

interposing the preformed adhesive therebetween so that said cutout portions are in alignment with the apertures and projections respectively;

urging the die plate and die support towards one another while heating the adhesive film to cause it to deform and to allow the die plate to rest on the projections; and

applying further heat to cure said preformed adhesive film thereby to form a bond between the die plate and the die support.

2. Process comprising the steps of making a bonded die plate and support assembly as claimed in claim 1, a stripper block having holes therethrough corresponding one with each of the plurality of punches, a plurality of punch bearing members arranged to fit loosely into the holes of the stripper block, and a set of punch mandrels one for each hole in the stripper block;

inserting the punch mandrels one into each aperture of the die plate;

threading said bearing members one to said mandrels;

- bringing together in alignment the stripper block and the die plate and support assembly to cause the bearing members to enter into said holes;

and bonding the bearing members into the stripper block. 

1. Process comprising the steps of making a die plate containing a plurality of apertures corresponding one with each of a plurality of punches, a die support extending over an area substantially equal to that of the die plate, the die support also containing apertures corresponding one with each of said punches and having projections raised to a predetermined height on one face thereof, and a preformed adhesive film of a thickness greater than the height of the projections having cut-out portions the positions of which correspond to said apertures and said projections respectively; positioning the die plate and the die support with their Respective corresponding apertures in alignment, said one surface of the die support facing the die plates; interposing the preformed adhesive therebetween so that said cutout portions are in alignment with the apertures and projections respectively; urging the die plate and die support towards one another while heating the adhesive film to cause it to deform and to allow the die plate to rest on the projections; and applying further heat to cure said preformed adhesive film thereby to form a bond between the die plate and the die support.
 2. Process comprising the steps of making a bonded die plate and support assembly as claimed in claim 1, a stripper block having holes therethrough corresponding one with each of the plurality of punches, a plurality of punch bearing members arranged to fit loosely into the holes of the stripper block, and a set of punch mandrels one for each hole in the stripper block; inserting the punch mandrels one into each aperture of the die plate; threading said bearing members one to said mandrels; bringing together in alignment the stripper block and the die plate and support assembly to cause the bearing members to enter into said holes; and bonding the bearing members into the stripper block. 